Type-3 metabotropic glutamate receptors regulate chemoresistance in glioma stem cells, and their levels are inversely related to survival in patients with malignant gliomas.

Drug treatment of malignant gliomas is limited by the intrinsic resistance of glioma stem cells (GSCs) to chemotherapy. GSCs isolated from human glioblastoma multiforme (GBM) expressed metabotropic glutamate receptors (mGlu3 receptors). The DNA-alkylating agent, temozolomide, killed GSCs only if mGlu3 receptors were knocked down or pharmacologically inhibited. In contrast, mGlu3 receptor blockade did not affect the action of paclitaxel, etoposide, cis-platinum, and irinotecan. mGlu3 receptor blockade enabled temozolomide toxicity by inhibiting a phosphatidylinositol-3-kinase/nuclear factor-κB pathway that supports the expression of O(6)-methylguanine-DNA methyltransferase (MGMT), an enzyme that confers resistance against DNA-alkylating agents. In mice implanted with GSCs into the brain, temozolomide combined with mGlu3 receptor blockade substantially reduced tumor growth. Finally, 87 patients with GBM undergoing surgery followed by adjuvant chemotherapy with temozolomide survived for longer time if tumor cells expressed low levels of mGlu3 receptors. In addition, the methylation state of the MGMT gene promoter in tumor extracts influenced survival only in those patients with low expression of mGlu3 receptors in the tumor. These data encourage the use of mGlu3 receptor antagonists as add-on drugs in the treatment of GBM, and suggest that the transcript of mGlu3 receptors should be measured in tumor specimens for a correct prediction of patients' survival in response to temozolomide treatment.

Quercetin and tamoxifen sensitize human melanoma cells to hyperthermia.

Hyperthermia produces regression of human cancer. Because hyperthermia has produced only limited results, attention has focused on searching for substances able to sensitize tumour cells to the effects of hyperthermia. The flavonoid quercetin has been reported to be a hyperthermic sensitizer in ovarian and uterine cervical tumours and in leukaemia. Quercetin and tamoxifen inhibit melanoma cell growth. We therefore investigated whether quercetin and tamoxifen can sensitize M10, M14 and MNT1 human melanoma cells to hyperthermia. We observed that both quercetin and tamoxifen synergize with hyperthermia (42.5 degrees C) in reducing the clonogenic activity of M14 and MNT1 and in inducing apoptotic cell death in all three cell lines. As revealed by flow cytometric and Northern blot analyses, quercetin and tamoxifen reduced heat shock protein-70 expression at both protein and mRNA levels. Our results suggest that quercetin and tamoxifen can be usefully combined with hyperthermia in the therapy of recurrent and/or metastatic melanoma.

Differential sensitivity of leukemic and normal hematopoietic progenitors to the killing effect of hyperthermia and quercetin used in combination: role of heat-shock protein-70.

Autologous bone-marrow transplantation (ABMT) is widely used in the treatment of acute leukemias where a matched sibling donor is not available for allogeneic transplantation. However, a major problem in ABMT is relapse, and ex vivo purging may be very important in preventing it. We show here that quercetin enhances the growth-inhibitory effect of hyperthermia (HT) in AML (19 cases) and ALL (6 cases) leukemic blasts. Furthermore, the inhibitory effect of this combined treatment resulted in leukemic-cell apoptosis. On the contrary, normal hematopoietic progenitors were neither growth-inhibited nor induced to apoptosis by HT-plus-quercetin treatment. To explain this difference in sensitivity of leukemic and normal hematopoietic progenitors, we analyzed the effect of quercetin on heat-induced expression of heat-shock protein-70 (HSP-70), which has been shown to be important in regulating thermosensitivity. We found that quercetin inhibits heat-induced HSP-70 expression both at protein and at mRNA levels in AML and ALL blasts. In normal CD34+ progenitors, the combined treatment with HT and quercetin did not reduce HSP-70 expression and did not induce cell apoptosis. Considering the difference in heat sensitivity of normal CD34+ and leukemic progenitors in the presence of quercetin, the combined use of HT and quercetin could constitute a purging protocol for ABMT.

T cell surface markers expression by immature human thymocytes in in vitro culture: role of Ia+ accessory cells.

Previous studies have indicated that the human thymus is composed of several discrete compartments. Cortical thymocytes are reactive with the monoclonal antibody anti-T6, whereas most medullary cells, unreactive with anti-T6, stain brightly with anti-T3 antibody, which defines mature T cell populations. By using an indirect immune rosette method, we isolated the minor thymocyte population (1 to 2% of all thymocytes) lacking both T3 and T6 but expressing T11 antigens. These cells could be maintained in culture supplemented with recombinant IL 2 (Rec-IL 2) for several days. Under these conditions, T3-T6- cells were shown to undergo phenotypic changes. In the absence of thymic macrophage (Mo), T3+ and T8+ thymocytes appeared in culture, whereas the development of T4+ cells strictly required the presence of Mo. The expression of T4 antigen could be largely prevented by the addition of anti-HLA-DR antibody, further indicating that Ia+ accessory cells had the ability to promote in vitro development of T4+ thymocytes. In the presence of Mo, not only T4+ but also T8+ cells were obtained. Double fluorescence staining with anti-T8-FITC and anti-T4-biotin demonstrated that after 12 days of culture, T4 and T8 antigens were mutually exclusive. Furthermore, during the course of these studies, we observed that under the culture conditions utilized (e.g., presence or absence of Mo), T3-T6-thymocytes failed to express the T6 antigen. Thus, the in vitro development of T cells bearing a mature phenotype could be obtained in the absence of intermediate expression of cortical (T6+) thymocytes.

OKT4/OKT8 ratio and serum beta 2-microglobulin in mycosis fungoides and chronic benign dermatitis.

Pre-treatment Serum Beta 2-microglobulin (S B2-m) and OKT4/OKT8 Ratio (T4/T8 R) were studied in 15 patients with Mycosis Fungoides (MF) and in 10 subjects with Chronic Superficial Benign Dermatitis (CSBD) in order to verify whether these parameters may lend support to an earlier differential diagnosis. S B2-m levels and T4/T8 R showed no significant difference in CSBD as compared to normal controls. MF patients displayed elevated S B2-m and T4/T8 R values in comparison to healthy controls and subjects suffering from CSBD (P less than 0.001). After photochemotherapy (PUVA), markedly decreased S B2-m and T4/T8 R values were observed in all patients but two who proved to be unresponsive to PUVA treatment. On the basis of reported data, S B2-m and T4/T8 R can be regarded as an additional tool to discriminate CSBD and MF when clinical and histological features are not significantly diagnostic. Finally, these parameters seem to provide reliable information in monitoring response to treatment.

Distribution of circulating mononuclear cells in short-term PUVA-treated psoriatic patients and healthy subjects.

Peripheral blood mononuclear cells (PBMC), as defined by monoclonal antibodies (OKT3, OKT4, OKT8, OK 1, Leu 7, Leu 11b) were determined in 10 psoriatic patients and in 10 healthy subjects before and after administration of short-term PUVA therapy. A comparison of the mean baseline percentages of the two groups showed a statistically significant increase in Leu 7+ cells (p less than 0.001) as well as a slight increase in OKM1 and OKT8 positive cells in the psoriatic subjects. After 21 exposures, these subsets showed a reduction towards control values, while a significant increase in OKT3 and OKT4 positive cells (p less than 0.01) could be observed only in the control group. These results indicate that short-term PUVA therapy is associated with changes in PBMC subpopulations. This modification, however, does not necessarily imply a disturbance of immune system function, including natural killer activity.